P0BF4: motor B phase U high must be interpreted in the disabled-output state

P0BF4 is the high-range circuit monitor for motor B phase U current sensing in the cited GM document. It evaluates the reported sensor value under an output-disabled condition. The code is not a stand-alone proof of a physical overcurrent event during motor operation.

Establish the specific threshold and state

The sensor output must exceed 700 A. GM requires the wakeup signal on and PWMOutputEnable FALSE. Those conditions belong with the captured value when a technician interprets the fault.

Ten qualifying counts among fifteen are needed at a 2.08 ms interval. These are internal detection parameters; they should not be converted into an external current-injection test or assumed to apply to unrelated inverter hardware.

Retain the offset-test dependency

The source allows the phase U offset monitor only when P0BF4 and its low counterpart are inactive. An absent performance code may therefore reflect inhibition while the high-range fault remains, rather than establish a healthy measurement channel.

Save the associated fault status and controller data before clearing memory. The table does not identify a defective wire or require replacing the inverter. The actual hybrid service procedure must guide safe diagnosis and verification. Disabled PWM does not prove the high-voltage system is isolated; trained personnel must establish safe access independently and confirm credible sensing after repair.

Source and applicability

GM 2010 10OBDG10 Hybrid Diagnostics, cited BPCM or hybrid-controller monitor only. Historical calibration values are not universal specifications; no per-code model, engine or hardware fitment has been established. GM PDF, physical page 296.